A couple of remarks regarding the gamma correction thing:

You should have:

The skydome must fill the entire sky - not only the camera view like DAZ's Environment prop. The texture is attached to either the alt-diffuse OR the ambient node.

gamma correction at 2.2 in the render settings.

Infinite light is NOT Diffuse IBL but a real infinite light

All color maps are set to Use current Rendersettings for gamma control (If you click on the node to load a new texture you can see what gamma setting it is set at)

All greyscale transmaps, bumpmaps, specular maps, displacement maps are set to Gamma control 1.0

I do not know which script you used, but check if this has done the above

The light color also plays a role in how the scene looks - I usually set it at pure white

The color of the skydome and ground also plays a role in the color of the scene because IDL uses those colors

Under normal circumstances IDL on with Gamma Control at 2.2 and an infinite white light with no other lights should light the entire scene including areas in the shadows

I do not know what you use the spotlights for and what overal effect you want to have, so I cannot tell you how to set those.

Remember that the (skin) textures play a large role as well - VSS helps you with that